Performance of a GridPix detector based on the Timepix3 chip

A GridPix readout for a TPC based on the Timepix3 chip is developed for future applications at a linear collider. The GridPix detector consists of a gaseous drift volume read out by a single Timepix3 chip with an integrated amplification grid. Its performance is studied in a test beam with 2.5 GeV electrons. The GridPix detector detects single ionization electrons with high efficiency. The Timepix3 chip allowed for high sample rates and time walk corrections. Diffusion is found to be the dominating error on the track position measurement both in the pixel plane and in the drift direction, and systematic distortions in the pixel plane are below 10 $\mu$m. Using a truncated sum, an energy loss (dE/dx) resolution of 4.1% is found for an effective track length of 1 m.Comment: To be published in Nuclear Instruments and Methods in Physics Research Section

A Survey of Positioning Systems Using Visible LED Lights

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.As Global Positioning System (GPS) cannot provide satisfying performance in indoor environments, indoor positioning technology, which utilizes indoor wireless signals instead of GPS signals, has grown rapidly in recent years. Meanwhile, visible light communication (VLC) using light devices such as light emitting diodes (LEDs) has been deemed to be a promising candidate in the heterogeneous wireless networks that may collaborate with radio frequencies (RF) wireless networks. In particular, light-fidelity has a great potential for deployment in future indoor environments because of its high throughput and security advantages. This paper provides a comprehensive study of a novel positioning technology based on visible white LED lights, which has attracted much attention from both academia and industry. The essential characteristics and principles of this system are deeply discussed, and relevant positioning algorithms and designs are classified and elaborated. This paper undertakes a thorough investigation into current LED-based indoor positioning systems and compares their performance through many aspects, such as test environment, accuracy, and cost. It presents indoor hybrid positioning systems among VLC and other systems (e.g., inertial sensors and RF systems). We also review and classify outdoor VLC positioning applications for the first time. Finally, this paper surveys major advances as well as open issues, challenges, and future research directions in VLC positioning systems.Peer reviewe

DESIGN OF A BURST MODE ULTRA HIGH-SPEED LOW-NOISE CMOS IMAGE SENSOR

Ultra-high-speed (UHS) image sensors are of interest for studying fast scientific phenomena and may also be useful in medicine. Several published studies have recently achieved frame rates of up to millions of frames per second (Mfps) using advanced processes and/or customized processes. This thesis presents a burst-mode (108 frames) UHS low-noise CMOS image sensor (CIS) based on charge-sweep transfer gates in an unmodified, standard 180 nm front-side-illuminated CIS process. By optimizing the photodiode geometry, the 52.8 μm pitch pixels with 20x20 μm^2 of active area, achieve a charge-transfer time of less than 10 ns. A proof-of-concept CIS was designed and fabricated. Through characterization, it is shown that the designed CIS has the potential to achieve 20 Mfps with an input-referred noise of 5.1 e− rms

A cost-effective, mobile platform-based, photogrammetric approach for continuous structural deformation monitoring

PhD ThesisWith the evolution of construction techniques and materials technology, the design of modern civil engineering infrastructure has become increasingly advanced and complex. In parallel to this, the development and application of appropriate and efficient monitoring technologies has become essential. Improvement in the performance of structural monitoring systems, reduction of labour and total implementation costs have therefore become important issues that scientists and engineers are committed to solving. In this research, a non-intrusive structural monitoring system was developed based on close-range photogrammetric principles. This research aimed to combine the merits of photogrammetry and latest mobile phone technology to propose a cost-effective, compact (portable) and precise solution for structural monitoring applications. By combining the use of low-cost imaging devices (two or more mobile phone handsets) with in-house control software, a monitoring project can be undertaken within a relatively low budget when compared to conventional methods. The system uses programmable smart phones (Google Android v.2.2 OS) to replace conventional in-situ photogrammetric imaging stations. The developed software suite is able to control multiple handsets to continuously capture high-quality, synchronized image sequences for short or long-term structural monitoring purposes. The operations are fully automatic and the system can be remotely controlled, exempting the operator from having to attend the site, and thus saving considerable labour expense in long-term monitoring tasks. In order to prevent the system from crashing during a long-term monitoring scheme, an automatic system state monitoring program and a system recovery module were developed to enhance the stability. In considering that the image resolution for current mobile phone cameras is relatively low (in comparison to contemporary digital SLR cameras), a target detection algorithm was developed for the mobile platform that, when combined with dedicated target patterns, was found to improve the quality of photogrammetric target measurement. Comparing the photogrammetric results with physical measurements, which were measured using a Zeiss P3 analytical plotter, the returned accuracy achieved was 1/67,000. The feasibility of the system has been proven through the implementation of an indoor simulation test and an outdoor experiment. In terms of using this system for actual structural monitoring applications, the optimal relative accuracy of distance measurement was determined to be approximately 1/28,000 under laboratory conditions, and the outdoor experiment returned a relative accuracy of approximately 1/16,400

Comunicações ópticas por câmera para sistemas de assistência à condução

Communications, whatever its type, is a pillar of our modern society. More specifically, communications by visible light, that show numerous advantages, from electromagnetic spectral efficiency and regulation freedom to energy saving (since it combine illumination and communication). As such, the automotive world is interested in this technology, in particularly, its application into the Intelligent Transport System (ITS). The objective of this work relies on the study and development of a demonstrator able to support VLC communication means in V2V (Vehicle to Vehicle) scenario, making use of the LED luminaries already implemented in nowadays cars. Since the outdoor implementation is one of the requirements, reception based in OCC (Optical Camera Communication) is a viable solution in this conditions. Also the signal processing/decoding is performed by a CNN (Convolutional Neural Network), this type of algorithm shows a huge decoding flexibility and resilience, which benefits the transmission system performance. All the project was done in collaboration with the integrated circuits systems group of Instituto de Telecomunicações de Aveiro and Exatronic Lda company, based in Aveiro and specialized in innovation and investigation (I+I), engineering and manufacturing of electronics.As comunicações, qualquer que seja o seu tipo, mostram-se como um pilar fundamental para a sociedade. Especificamente as comunicações por luz visível, que apresentam inúmeras vantagens, desde a eficiência espectral e mais liberdade de regulamentação, até à energética pois alia duas caracteristicas distintas (iluminação e comunicação) numa só. Como tal, o mundo automóvel apresenta-se como um dos posíveis interessados na aplicação desta tecnologia, mais propriamente a aplicação como parte integrante do sistema inteligente de transportes (ITS). Este trabalho tem como objectivo o estudo e desenvolvimento de um demonstrador capaz de estabelecer um link de comunicação V2V (Vehicle to vehicle) por meio da modulação da luz visivel emitida pelas iluminárias LED já equipadas actualmente nos veículos. Sendo a implementação exterior um dos requerimentos deste sistema, a rececção através de OCC (Optical Camera Communication) mostra-se assim uma solução viável. Assim como o processamento do sinal recebido, que é efectuado por meio de CNNs (Convolutional Neural Networks), que mostram flexibilidade e resiliência, o que benefecia a capacidade do sistema de transmissão. Todo o projecto foi realizado em colaboração com o grupo de circuitos integrados do Instituto de Telecomunicações de Aveiro e a empresa Exatronic Lda, sediada em Aveiro, e especializada em inovação, investigação (I+I), engenharia e produção de eletrónica.Mestrado em Engenharia Eletrónica e Telecomunicaçõe